The Hidden Phenomenon That Could Ruin Your Old Discs

The Hidden Phenomenon That Could Ruin Your Old Discs. Ernie Smith. Motherboard. February 6, 2017.
     An article about regular CD and DVD optical discs and the problems that cause them to deteriorate.  "CDs and DVDs were sold to consumers as these virtually indestructible platters, but the truth, as exemplified by the “disc rot” phenomenon, is more complicated."  Early research showed that problems with the reflective layer could make the disc fail in 8 - 10 years. Or the degradable dye used in record-able discs will break down. The disc degradation sometimes looks like a stain or discoloration, or tiny pin pricks on the disc surface. "The eventual decay of optical media is a serious situation, whether you're a digital archivist or simply someone who wants to watch a movie on a weird format like a Laserdisc."

A Library of Congress preservation specialist said that the disc destruction showed up in three different forms: the "bronzing" of discs;  small pin-hole specs located on the discs; or "edge-rot".
Five facts about disc rot, according to the Library of Congress:

1. Discs with significant errors are often still at least partially readable. This depends on the type of disc and where the error occurs.
2. A scratch at the top of a CD is more problematic than one on the bottom, because scratches to the top surface can penetrate through and damage the reflective layer.
3. DVDs generally have better integrity than do CDs but layers can delaminate over time. Dual-layer discs tend not to hold up so well.
4. Recordable discs, and particularly DVDs don't last as long, due to the degradation of the organic dye used. A poorly recorded disc tends to wear out more quickly.
5. Proper storage and handling helps. A well-made commercially pressed disc can last many decades if stored and handled properly. Discs stored in harsh environmental conditions with elevated temperature and/or humidity will have shorter expected lifetime.

Digital Preservation Matters.

Alternatives for Long-Term Storage Of Digital Information

Alternatives for Long-Term Storage Of  Digital Information. Chris Erickson, Barry Lunt. iPres 2015. November 2015.   Poster  Abstract
     This is the poster and abstract that Dr. Lunt and I created and was presented at iPres 2015. The most fundamental component of digital preservation is storing the digital objects in archival repositories. Preservation Repositories must archive digital objects and associated metadata on an affordable and reliable type of digital storage. There are many storage options available; each institution should evaluate the available storage options in order to determine which options are best for their particular needs. This poster examines three criteria in order to help preservationists determine the best storage option for their institution:

1. Cost
2. Longevity
3. Migration Time frame

Each institution may have different storage policies and environments. Not every situation will be the same. By considering the criteria above (the storage costs, the average lifespan of the media and the migration time frame), institutions can make a more informed choice about their archival digital storage environment. The poster has more recent cost information than what is in the abstract.

Digital Preservation Matters.

The National Film Board’s CTO offers a close-up look at its digital archiving project

The National Film Board’s CTO offers a close-up look at its digital archiving project. Shane Schick. IT World Canada. October 16, 2015.
     The Canadian National Film Board has been putting together the technology, processes and policies to change the way films are produced, collected and stored. The NFB collection needs a particular set of metadata because of the versions produced.

Archiving digital content is an ongoing challenge for many organizations because the volume of content and also "the fact that formats change, and ensuring the long-term accessibility and quality can be uncertain". The organization tries to stay ahead of the difficulties by adhering to to four ‘golden rules’ of archiving. These include:

1. There must be a process to continually check the integrity of the data which has been stored.
2. Open file formats should be used whenever possible, in order to avoid frequent data migrations.
3. Obsolescence of the storage hardware should be assumed as inevitable.
4. Two copies of all content or media assets should be maintained on different technologies, in different locations, which is the "most critical" part.

While LTO tapes are often used in the industry, the organization uses ASG’s Digital Archive (based on Sony’s Optical Disk Array). These discs have a 50 year life expectancy. They still use LTO for backup, but now they have the optical element that they can go back to. “The archiving system allowed us to think beyond the film.”  The new way of thinking is very open. "We can ingest content as we produce it."  

Digital Preservation Matters.

Testing a Permanent Digital Storage Archive – Part 2: OAS and Rosetta

Testing Permanent Digital Storage Archive – Part 2: OAS and Rosetta. Chris Erickson. September 10, 2015.

     The Optical Archive System from Hitachi LG Data Storage fits in a server rack and can contain 10 units, called libraries. Each library unit contains 100TB of data storage on 500 long-term optical discs. More information at Rosetta Users Group 2015: New Sources and Storage Options For Rosetta (slides 13 – 16) or this YouTube video.

Connecting the OAS and Rosetta Systems:

Once the optical archive was installed in our Library, it was then connected to our Rosetta system, which was very easy to do and only took a couple of minutes. In the Rosetta administrative module I created a new File storage group with the OAS path and the storage capacity. The IE and Metadata storage groups were left as they were, directed to our library server. The files in those groups are much smaller and accessed more often than the files. I then added a new storage rule so Rosetta could determine whether to write the files to our library server, to our Amazon storage account, or to the OAS.

Write functionality:

When the data is written to the optical discs a fixity check is done to ensure that the file is 100 % accurate. Once the file is written to the optical disc, the data is permanent.  Even if the system were to go away, the data discs are permanent and could still be read on any Blu-ray device.  I ingested a couple hundred GBs into Rosetta which were then written out to the OAS discs. (Overall I added over 4 TB of data.) We never encountered any difficulties with writing data to the OAS. We did try to disrupt or corrupt the writing process to see if we could get it to fail or to write bad data, but even our systems engineer with root access was unable to affect the data in any way.

Normally our test Rosetta system is configured for only a small number of files, so there is limited processing space, about 45GB. (Our live production Rosetta system has 2 TB of processing space). Because of the limited processing space on the test server, I could not run an unrestricted ingest without filling up the disk space. So I ingested a limited number of items at a time and then also cleared the processing space before ingesting more. The chart below shows the ingest amounts for two of the afternoons when the ingest processes were run-each took about 5 hours. (An unrestricted ingest would likely result in at least four times as many items per day.)

IEs	Files	GBs
8,019	50,856	352.53
6,639	48,736	346.42

 

Read functionality:

This is an optical device, so I did not know if Rosetta would be able to read the discs. And since it is an optical device the OAS has to locate the correct disc and load the disc in a drive to retrieve the data (there are 12 read / write drives for each library). The retrieval process can take up to 90 seconds. Our Rosetta system is used as a dark archive, so the retrieval time was not a problem. The question was whether or not Rosetta would wait while the file was being retrieved or if it would time out. From the first request, the OAS read functionality worked flawlessly. Rosetta worked well with the retrieval / access time while the disc was retrieved and the file read. Once the disc was in the drive, access for any other files on the disc was about as fast as if it were on spinning disc.

Here is a chart of access times for one of the groups that I checked:

Title	Files	Item size	Access time
	in Item	MB	Min:sec
List of titles of genealogical articles	9	169	1:16
Jackson collection image	2	16	1:20
Jackson collection image	2	8	0:23
John O. Bird children	1	6	1:25
Cardston Alberta Temple	1	5	0:18
Piano	1	11	1:34
F Edwards	1	2	0:14
E O Haymond	1	4	0:09
Taj Mahal,	2	14	0:27
Taj Mahal,	2	14	0:09
Millie Gallup	1	5	0:14
History of the Lemen family	9	528	0:17
The Boynton family.	9	405	0:11
Register and almanac	9	537	0:25
The crawfishes of the state	9	214	0:14
Tank	1	6	0:20
Parley D. Thomas	1	4	0:19
Blake family : a genealogical history	9	146	0:10

 

From the access time column it is obvious when a new disc is retrieved, as the time is over 60 seconds. Once the disc has been loaded then the access time for subsequent files is much lower.These access times are for the master files, which can be quite large.

The setup process, writing and reading all went extremely well. The next step was to run an automated fixity check on the OAS files from within Rosetta.
(Updated to clarify and answer questions.)

Digital Preservation Matters.

Testing a Permanent Digital Storage Archive – Part 1

Testing a Permanent Digital Storage Archive – Part 1. Chris Erickson. September 9, 2015.

     For about the past seven years I have been testing the M-Disc permanent digital storage media. The M-Disc is designed to use inert, permanent materials, so that digital data written to the discs are permanent.

The original M-Discs were in the standard DVD format that can hold up to 4.7 GB. This works well for MB or GB collections but it becomes a bit cumbersome when working with many TBs. It takes 213 DVDs to hold 1 TB of data. (I am looking forward to the 200 GB M-Discs, which would be 5 discs per TB.)

I suggested to the people at Millenniata that it would be much more useful for large data archives if they could take a tape library and replace the tapes with M-Discs. As long as I was wishing, I would like it to include some additional features:

• network accessible
• drag and drop capability to speed up the file ingesting
• disc spanning to make migrating old CDs easier, as well as storing large files
• fixity checking as a built in process
• an index of the system for retrieval and management
• automatic replication of discs to make multiple copies
• ability to migrate to new discs with a higher capacity when they became available.  

And, of course, increase the disc capacity and decrease the price. Then we would have the perfect permanent storage.

Well, the capacity has increased from 4.7 GB to 100 GB per M-Disc and that will hopefully double soon. The price has dropped 10 fold. And Hitachi LG Data Storage (HLDS) has actually built the storage system. We’ve been talking with them since 2012, and so in February of this year they installed a test system at our library, the HLDS Optical Archive System (OAS). The storage system, which fits in a server rack, can hold up to 1 PB of archival storage space; we were testing a single storage library with 100 TB of storage space. The OAS uses a server for the processing, indexing and ingest functions. There is a YouTube video available.

The OAS uses long term Blu-ray discs; each is 200 GB. The optical discs we were testing were their standard discs which have been tested and certified for 50+ years. Millenniata hopes to have their 200GB discs available soon, and those could be used as well.  These are industry standard format Blu-ray optical discs. We were interested in these for long term storage because of their longevity and reduced operating cost, since they don’t have to be continually spinning. (Blu-ray Disc is increasingly used as an archival storage solution because of the longevity of the discs and the cost savings). The testing was supported by the HLDS group in California and they were extremely helpful with installation, training, frequent visits to our library, and weekly phone calls.

The Optical Archive System met all the functions on my wishlist. The question now was: How will it work with our Rosetta digital preservation system?

(Updated to clarify and answer questions.)

Related posts:

• Permanent Digital Data Storage: Tape, solid-state, and discs
• Keeping Data For A Long Time
• Facebook uses 10,000 Blu-ray discs to store 'cold' data
• Optical Storage Posts

Digital Preservation Matters.

Permanent Digital Data Storage: Store it and forget it

Permanent Digital Data Storage: A Materials Approach. Barry Lunt, Robert Davis, Douglas Hansen, John Dredge, Hao Wang and Matthew Linford. International Conference on Preservation of Digital Objects.  iPres 2013.
      "For deep archival storage, the ideal is to be able to create the desired artifact, then store it and forget about it, knowing that whenever we wish to access it again, it will still be there, and we will still be able to read or observe it." Using ancient historical materials as examples, archival storage should be made from materials which either do not oxidize (such as gold), or else are by nature fully oxidized or chemically-reacted materials. 

Merely making a mark in a layer of recording material is not robust data storage solution. By using layers of inorganic, stable materials, a digital medium can be created for recording and playback. Optical data recording has a significant advantage when it comes to data longevity because accessing the object does not involve any contact between the media and the recording and playback mechanism. This means the file can be read an infinite number times without any degradation. "And the relative simplicity of the playback mechanism means that, if the data persists on the media, future optical playback systems will readily be capable of being adapted as necessary to read data stored permanently on optical discs".

A materials approach to the problem of permanent digital data storage shows that by using extremely durable materials they can create a permanent storage medium. Permanent, in this case, does not mean 'forever', since "nothing that science acknowledges is permanent". The paper uses the ANSI/AIIM definition of permanent: “Life Expectancy: Length of time that information is predicted to be retrievable in a system under extended-term storage conditions. Rating for the ‘life expectancy’ of recording materials and associated retrieval systems. NOTE: The number following the LE symbol is a prediction of the minimum life expectancy in years for which information can be retrieved without significant loss when properly stored under extended-term storage conditions, e.g., LE-100 indicates that information can be retrieved for at least 100 years of storage."

The authors propose that a practical definition for permanent digital data storage would be: "Permanence: The ability of a digital data storage medium to last at least two hundred years without significant deterioration under normal use and storage conditions in libraries and archives. This means there is a 99.99% confidence of complete data recovery using the intended read mechanism or hardware."

Currently the only digital medium that can last for more than a decade or so is the M-Disc, from Millenniata, Inc. All other digital data storage media have very serious limitations when it comes to permanence. How can the life expectancy of a medium be established? One way is using the long accepted methods of accelerated testing using the Arrhenius and Eyring equations as the scientific foundation.

The paper looks at solid-state storage media and computer tape and explains why they are not permanent. None of the current solid-state storage options are viable for permanent digital data storage. The problem with magnetic media is that "the magnetic domains begin to relax, slowly reverting to their original random orientation, and slowly degrading the difference between the encoded 1s and 0s. Eventually, so many of these bits will have degraded that reading a file back will have become impossible." Magnetic tape uses an organic material as a binder, which will degrade with time; the recording layer separates from the polyester substrate causing permanent data loss. There is an urgent need for some way to store digital data permanently. The M-Disc is one viable solution and "we are well on our way to providing two additional media for permanent digital data storage."

Just having a permanent storage medium is not a complete solution without a way to read the data far into the future. But a permanent medium is indispensable for deep archival data storage. "Some future generation may struggle to learn how our data was stored, but if all the marks on the Rosetta stone had faded away, deciphering them would never have been possible. It is relatively easy and inexpensive to read the marks made on optical discs - the hardware is widely available and optical discs are the most widely adopted digital storage medium in history. And wide adoption is a powerful predictor of relative permanence of readability."

Related posts:

• Permanent Digital Data Storage: Tape, solid-state, and discs
• So what's up with the M-Disc? Part 1   Part 2
• Fighting entropy and ISIL, one image at a time
• Preserving Our Digital Heritage
• Dataliths vs. the digital dark age

Digital Preservation Matters.

So what's up with the M-Disc? Part 2

So what's up with the M-Disc? Part  2. Chris Erickson. 19 August 2015.
     Our library had some important digital images that could not be recreated if they were lost. I was a bit nervous about those, realizing that it was my responsibility to maintain them long term. We tested lots of potential solutions, including creating an in-house preservation system in about 2004.These things were all fine, but they didn't feel like a solution. With the M-Disc there was at least a possible solution and I wanted to find out if it was really better than what we were doing at the time.

The M-Disc was invented at BYU, and Barry Lunt had worked with the library on this. So the library was involved in the testing process from very early on. We went through a number of tests until we felt they were ready to use to preserve a major collection, and then setup a testing process. We migrated the Herculaneum papyrus images from gold CD to the M-Discs.

The burning and verification processes took more than an hour for each DVD. All images had been  examined beforehand to make sure they were good, then checksums for all the images were generated. We used the Nero software for burning and it generated helpful reports for each disc. Trying to burn discs from content across the network sometimes caused buffer errors, so we always put the content on the workstation and created an ISO image; the ISO image would then be burned to the disc.  After the disc was created, we verified the disc with Nero, with a disc check utility, and a custom routine that sampled random spots on the disc. We also had a disc analyzer that would do a low level check of the disc and report any read errors by the various categories. If there were read errors above an established threshold, the disc would be discarded and the images re-burned. The discs were tested on three separate computers. The final test was to copy the images from the discs to the workstation and then compare the checksums from the newly copied images to the checksums of the original images.  The tests were run right after burning, after one month, and then after one year. All tests and results were logged.  It was interesting to also see the tests that military did on optical discs, including the M-Discs, in the China Lake report.

From all the tests, we concluded that the M-Disc was the best long term storage option, and it is now used by several areas on campus. The library Digital Lab burns M-Disc copies of the images they create. They have 12 drives that can burn from either the PCs or Mac computers in the lab. The M-Discs are put in labeled sleeves in archival boxes, then accessioned into Special Collections. We also use the Rosetta software for our Digital Archive (tape backups and an annual tape archive are stored off site in the Granite Mountain Vault). The University Records department also uses the M-Discs, particularly for departments that want 'Permanent In Office' records.

The questions I often get asked:

1. Do I really think the M-Discs will last 1000 years? I can't image what computing will be like in 100 years, much less 1000 years. But I fully expect the M-Discs, with care, will last that long. Matthew Linford, a co-creator of the M-Disc, is a professor of Chemistry and Material Science. His published research papers show the M-Discs are made of inert materials that are not affected by environmental factors. The scientific materials approach shows there aren't any 'failure mechanisms' that would cause the discs to fail. It is unchanged by magnetism, temperature, light, humidity; with M-Discs, there is no possibility of bit rot or bit flips. The disc writing process actually makes irreversible physical pits on the M-Disc which will not fade over time. 
2. Will there be a way to read the M-Discs in 1000 years? I expect that DVD and Blu-ray discs will continue to be used for at least the next 25 years, if not longer. If you have the bits, there will always be a way to read them. The optical discs are written and read by standard documented technology, and the reading mechanisms, as one paper puts it, would be a trivial matter to build. 
3. Do the M-Discs require a special drive? Many optical drives (made by different manufacturers such as LG, Pioneer, Samsung, Panasonic, ASUS) can write the M-Discs. Since they follow the DVD and Blu-ray specifications, M-Discs can be read by any DVD or Blu-ray drive. The discs are available from mdisc.com, Amazon.com, Best Buy, or other places.
4. Isn't it difficult to burn a lot of optical discs? It is time consuming to burn lots of discs. The 100 GB M-Disc is available, and I am anxious to get the 200 GB M-Disc, so there would be only 5 discs per TB. I had suggested they build a 'tape library-like' device for the M-Disc so the discs would be easier to write. Hitachi LG Data Services has now built an Optical Archive System.  It can hold 1 PB of optical discs in a server rack. We have been testing the OAS in our library since about March, (I think it is great) but that is another post for another day.

Last point: The main reasons we use the M-Disc isn't because we need the data to last 1000 years. The main reasons are:

1. I want to decide when or if I will migrate the data to another medium. I don't want that decision to be made for me every few years based on an expected failure date for magnetic disk or tape. 
2. The longer the media lasts and the more reliable it is, the fewer times I have to migrate or check the data, and that saves money, time, and reduces the risk of data corruption.
   

And no, I don't own stock in the M-Disc. But I do use them at home for my family photos and documents.

Digital Preservation Matters.

So what's up with the M-Disc? Part 1

So what's up with the M-Disc? Part 1. Chris Erickson. August 18, 2015.
     There have been a number of questions about the M-Disc lately and I thought I would add my thoughts (without my work records here to jog my memory). I've been working with M-Discs since about the beginning. Some background: In the late 1990's a department on campus dedicated to the preservation of ancient texts began using multi-spectral imaging on unreadable ancient documents, such as Petra scrolls, Herculaneum papyrus scrolls, and others. The master images they produced were stored on gold CDs since these were supposed to last 300 years. However, our annual checks on the tens of thousands of CDs showed a yearly loss rate of 2-5% (we had several copies of all the discs so we could refresh them as needed). Looking for a way to resolve the failing discs led to discussions with Dr Barry Lunt, who created the M-Disc with Matthew Linford and others. We have tested the discs since 2008-2009 and gave feedback to the company (Millenniata). The first large collection we created was the Herculaneum images, which we migrated from CDs to the M-Disc DVD in February 2010. I continue to check the discs periodically and there haven't been any problems with them. The discs have worked well for us.

Here are few of my early posts about the M-Disc:

Millennial disc guarantees data preservation. Logan Bradford. Daily Universe. September 15, 2009.

Barry Lunt, a BYU information technologies professor, will launch a product with the company, Millenniata, that produces a disc just like a CD or DVD that will last up to 1,000 years. He learned, through his seven years working for IBM in computer data, that data on CDs and DVDs would decay and be lost over just a few years because of optical discs’ ephemeral qualities, such as when they are exposed to sunlight and humidity. [We have been testing these discs and writers.]

Startup crafts DVD-Rs for the 31st century. Rik Myslewski. The Register. 23 July 2009.

The Millenniata company has developed a new DVD-R technology that it claims will be readable for 1,000 years. The Millennial Disc Series is designed to eliminate the need for governments, financial institutions, libraries, and others to regularly refresh and rotate their digital-data collections. The data is etched into a "carbon layer with the hardness of a diamond". It requires a specialized writer and discs [but readable on any DVD player]. The discs are stable from minus 100° to plus 200° centigrade, and are dunked in liquid nitrogen as part of the testing. These discs are one element of a data preservation strategy.

Millenniata continues to make progress with its patent-pending Millennial Disc and Millennial Writer. Press Release. February 2, 2009. This press release has information about a new optical disc that has been developed. It is designed to be a permanent archiving product that has no degradable components and “safely stores data for 1,000 years”. The technology makes a permanent change to the disc. It is referred to as Write Once Read Forever™ and can be read in a standard DVD drive. [check back for test results.]

Digital Preservation Matters.

Permanent Digital Data Storage: Tape, solid-state, and discs

Permanent Digital Data Storage: An Overview. Barry M. Lunt, Matthew R. Linford, and Robert C. Davis. Brigham Young University. ISOM Conference. Received PDF August 2015. [From author's  version; not yet available on line.]
     Research shows that digital storage, whether optical, solid state, or tape, can be permanent and could potentially last over 100,000 years if permanent materials are used. The failure mechanisms are well documented. Knowing what materials to use to eliminate the failure mechanisms is the key to permanent digital storage.

Computer data storage has always been ephemeral because of the emphasis on density and speed. There has been little interest in developing a permanent way to store digital data. The authors, an engineer, chemist, and physicist, believe "that the optimal storage media does not need to be refreshed nor stored in special conditions, and that a store-and-forget approach (like printing books and storing them on shelves) is best because it is the simplest."

Permanent Storage Options and approaches

• Optical disks. The dominant failure mechanism is dye fading which can be removed by using permanent materials. 
• The media they developed (M-Discs) make permanent physical and optical marks on a standard DVD or Blu-ray format disc.
• Optical discs are a viable option for archival storage of large amounts of storage
• This permanent format is essentially guaranteed for many decades or centuries to come
• Hard disk drives are not permanent. The failure mechanisms, which are fairly well known, are predominantly mechanical. A materials approach cannot solve these problems.
• Solid-state storage. A materials approach has produced storage elements capable of lasting as long as integrated circuits; the failure rate of such circuits is measured in Failure In Time, or about 114,155 years. This is a permanent form of preservation. Their research has solved the dominant failure mechanism of early permanent programmable solid state storage.
• Permanent optical tape. Their materials-research shows that if correct materials are used, computer tape can also be permanent and the permanent tape would "match the density of LTO-5, allowing about 2 TB per cartridge. The price of the media should be equivalent to that of magnetic tape."

Optical discs, solid-state storage, and computer tape can all be made to store data permanently and last hundreds or thousands of years.

Related posts:

• How Long Is Long-Term Data Storage? 
• Dataliths vs. the digital dark age
• Millenniata Announces Results of ISO/IEC 10995 Standard Tests
• Start-up to release 'stone-like' optical disc that lasts forever

Digital Preservation Matters.

Keeping Data For A Long Time

Keeping Data For A Long Time. Tom Coughlin. Forbes. June 29, 2014.
     Keeping information for a long time has always been a challenge.  Thermodynamics doesn’t favor information lasting a long time and so to make that happen people have to spend effort and energy. Deciding how to create a long-term archive involves choosing the right storage system with the right technology under the proper environmental conditions.  This can be combined with migration and replication practices to improve the odds of keeping content useful and accessible for an extended period of time. A conference looked at digital storage for long term archiving and preservation.Some of the technologies:

• It appears conventional flash memory may not have good media archive life and should only be used for storing transitory data
• Hard disk drives are used in active archives have problems because they wear out and even if the power is turned off the data in the hard disk drive will eventually decay due to thermal erasure  
• Digital magnetic tape under low temperature/humidity is a good candidate for long-term data retention  
• Optical storage has also been used for long-term data retention and should last at least several decades. Facebook has a 1 PB prototype that should reduce the storage costs by 50% and the energy consumption by 80% of their Hard Disk storage
• Sony said their properly made archival grade optical discs should have a shelf life of 50 years.
• Hitachi Data Systems showed costs for 5 PB of content over 75 years is less than frequent tape and HDD replacement.

A lot of digital data has persistent value and so long term retention of that data is very important. It is estimated the storage for archiving and retention is currently a $3B market growing to over $7B by 2017. "Magnetic tape and optical disks provide low cost long-term inactive storage with additional latency for data access vs. HDDs due to the time to mount the media in a drive.  Thus depending upon the access requirements for an archive it may be most effective to combine two or even three technologies to get the right balance of performance and storage costs."

Related posts:

• How Long Is Long-Term Data Storage? 
• Storage Trends Around Computex 2015
• Preserving Our Digital Heritage

Digital Preservation Matters.

Blu-ray Disc Association to Commence Licensing of Ultra HD Blu-ray

Blu-ray Disc Association to Commence Licensing of Ultra HD Blu-ray. Press release. August 6, 2015.
The Blu-ray Disc Association will start licensing the Ultra HD format August 24, 2015. The format will enable consistent and reliable delivery of Ultra HD content. Ultra HD Blu-ray players will also be required to play back current HD Blu-ray Discs.

Digital Preservation Matters.

How Long Is Long-Term Data Storage?

How Long Is Long-Term Data Storage? Barry Lunt. IS &T Archiving Conference. 2011.

    This paper looks at "In the context of archiving of physical documents, long-term storage has long been accepted to mean centuries." Since digital documents are much more ephemeral, archivists need to be aware of the technologies for preserving digital data and what can be expected for the long term. Results of several studies show that, with one notable exception, digital data cannot be expected to endure using any existing technologies.

Besides mechanical wear, oxidation, corrosion, and breaking of chemical bonds the most common failure mechanisms for materials, including digital data. Elevated temperature, humidity, and exposure to light increase the likelihood of failure, which is why archival storage relies on a controlled environment to reduce temperature, humidity and light.  The digital storage technologies, magnetic, solid-state, and optical, has known failure mechanisms, which have been studied. The studies of life expectancy for hard disk drives “eliminates HDDs as an archival storage option”.

The best way to guarantee that data will be readable in the future is by how widespread the adoption is. With data storage, "by far the most widespread formats in the history of digital data are the three main optical disc formats: CDs, DVDs and BDs". There are billions of optical readers in use today, and hundreds of billions of discs; no other digital storage technology even comes close.   While this does not guarantee long term persistence far into the future, the probability is extremely high. "If there is data still extant in these formats 500 years from now, it would be a relatively trivial matter to access that data".

Digital Preservation Matters